The one thing that I really like with using Ububntu is the amount of shortcut keys that you can use. Shortcut keys can really speed up your tasks, and make like so much more easier for you. I have listed what I find the most useful shortcuts below. I have decided to leave out the ones that I think everyone will know - like the Copy & Paste etc.
Some of the below shortcuts may require Compiz to be enabled on your Ubuntu system to work.
Switch Workspaces in Ubuntu (win + E)
1. Win +E - Shows all workspaces in a nifty way and lets you switch between workspaces easily.
2. Alt + Ctrl + Left/Right Arrow - Move to Workspace on Left/Right
3. Alt+Ctrl + Shift + Left/Right Arrow - Move current window to another workspace
4. Alt + Shift + Up Arrow - This initiates a cool looking window switcher interface with which you can switch between windows using Arrow keys while holding Alt + Shift.
Ubuntu Window Switcher (Alt + Shift+ Up Arrow)
5. Alt + F9/F10 - Minimize/ Maximize current window.
6. Alt + F5 - UnMaximizes Current Window.
7. Alt + F7 - This shortcut activates the move window option that lets you move current window using arrow keys. You can even move window to
8. Alt + F8 - Resize current window with arrow keys.
9. Ctrl + Alt + D - Show Desktop/ Restore open windows if show desktop used earlier
10. Alt + Shift + Tab - Switch Windows in Reverse Direction as done using Alt+Tab
11. Shift + Ctrl + N - Create New Folder, Very useful shortcut
12. Alt + Enter - Show properties of a selected file/folder without requiring to right click on it and select Properties.
13. Ctrl + 1/2 - Change folder view to icon/list.
14. Ctrl + W - Closes the current Nautilus Window
15. Ctrl + Shift + W - Closes all open Nautilus Windows
16. Ctrl + T - Open a new tab in Nautilus
17. Alt + Up/Down Arrow - Move to Parent Folder/ Selected folder
18. Alt + Left/Right Arrow - Move Back/forward in Nautilus
19. Alt + Home - Move directly to your Home Folder
20. F9 - Toggle display of Nautilus Side-pane
21. Ctrl + H - Toggle Display of hidden files and folders
22. Ctrl + Alt + L - Quick shortcut to Lock Screen if you nipping to the loo
23. Alt + F1 - Open Applications Menu
24. Alt + F2 - Open the Run Application dialog Box
25. Win + Mousewheel - Zoom in / Zoom out Desktop. This shortcut is useful if you are having a wireless keyboard/mouse.
If you know of any other useful Ubuntu shortcuts, feel free to share them with everyone in comments below.